Vacuum-operated brake



May 4, 1937. J. H. HUNT VACUUM OPERATED BRAKE Filed July 20. 1933 mm 60 m m mM Patented May 4, 1937 4 UNITED STATES PATENT OFFICE VACUUM-OPERATED BRAKE John H. Hunt, Detroit, Mich., assignor to Gencral. Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 20, 1933, Serial No. 681,267

1 Claim. (01. 188181) This invention relates to power-operated de- 62on the pedal 9 whereby the initial movement vices and more particularly toa fluid pressure of the pedal will move the rod 50. operating device for actuating vehicle brakes. Secured to the piston rod is a bracket 51 to An object of the invention is to improve the which is pivoted a lever or pendulum 59 having 5 operation of brakes actuated by fluid pressure a weight 6| at its lower end. The upper arm of 5 means. the lever 59 is connected by a link 63 to a ring A further object is to associate witha vacuum- 65 slidably mounted on the piston rod and operated brake actuating mechanism a manually adapted to be moved by a clockwise rotation of adjustable automatic control for said vacuumlever 59 toclose a plurality of openings 55 in the actuating mechanism. piston rod. 10 Other objects and advantages will be under- An arm 61 of bracket 51 carries clamped therestood from the following description. to the end of a flexible cable housing 69. The

- On the accompanying drawing Figure l is a other end of the cable housing is secured by suitview in side elevation, partly in section, of one able fastening means (I to the instrument board.

embodiment of the invention. Through the flexible housing extends an operating 15 Figure 2 is a similar view of a second embodicable 13, the instrument board end of the cable ment. being provided with an operating knob 15. Be-

Referring to Figure l, numeral 5 represents the tween the other end of the flexible cable and the floor boards of an automobile vehicle, and 'l is a lever 59 is a spring 11, which spring normally part of the instrument board within the operholds the lever against the stop 60. By actua- 0 ators compartment. The brake pedal is shown tion of the knob 15 the tension of the spring 11 at 9 and is pivoted at II. This pedal has an arm may be varied whereby the resistance to clockl3 to which is pivoted by a link l5 a lever l1. wise rotation of the lever may be controlled.

7 The upper end of lever IT has limited movement The operation of the device is as follows:

* within a notch l9 in arm 13. Adjacent this end When the pedal 9 is released the parts are in the 5 of the lever I! there is connected a brake-operatpositions as, shown. Chamber 3'! is evacuated ing rod 2|. by its connection with the engine manifold A fluid pressure cylinder 23 is suitably secured through conduit 35. Spring 81 holds the rod 50 pivotally as at 25. Within the cylinder is a piston in the position shown whereby valve 41 is closed 21 secured by fastening means 29 to the enlarged against shoulder 34 by the spring 49 and the 30 end 3| of a hollow piston rod 33, there being a openings 43 and 4! cause the left side of the shoulder 34 between the two parts. A conduit piston to be evacuated. When the pedal is de- 35 connects the chamber 31 of the cylinder to pressed rod 50 is first moved to the right, wherethe engine manifold. On the other side of the upon the spring 49 closes the valve 45 over the 35 piston from chamber 37 is a chamber 39 which opening 43. Upon a slight further movement of 35 is in communication with the enlarged head 3 the pedal and rod 5| the abutment 53 moves valve by the provision of openings 4|. The piston 21 41 and opens communication between chamber has an opening 43 which may be closed by a 39 and the atmosphere through the hollow piston disc-shaped valve 45. The hollow piston rod 33 rod and openings 55. The unbalanced pressure may be closed from communication with the on the two sides of the piston causes the piston 40 space within the enlarged head 3! by a second to move to the right, this movement operating valve 41, this valve being designed to engage the through rod 33, lever ll, and brake rod 2| to shoulder 34. Reciprocable through the piston apply the brake. The movement of the pedal rod 33 is a rod 59. The valves 45 and 4! are when pushing rod has also caused a relative 5 mounted on this rod between abutments 5| and movement to take place between the upper arm 45 53. A spring 49 is located between the valves. l3 and the upper end of lever I? such that the This spring tends to hold valve 45 against the upper end of lever ll lies adjacent the right end end abutment 5| or against the wall of the piston wall of the notch l9 (not the left end wall of surrounding opening 43. The spring also serves Figure 1). The subsequent movement of lever 50 to position the valve 41 against the wall 34. The I! by the piston will cause it to swing back to- 50 rod 59 is provided with another abutment 83 ward the position shown. In the event that the which is engaged by a spring 8| seated against a pedal movement is stopped the lever will actually transverse wall 86 within the piston rod. This rotate back to the position illustrated. If it does spring 8| is of sufiicient strength to normally reach the position shown, the movement of the hold the rod 50 closely adjacent a depending arm piston relative to rod 50 will close the air open- 55 ing and the brake will be held applied with a given degree of force until the pedal is released to restore the rod 5!! to its initial position. Additional brake-applying force is obtained by a continued depression of the brake pedal.

The movement to the right of the piston and its rod 33 exerts a pull on lever I'I tending to rock lever I'I. This is resisted by tension in brake rod 2i tending to oppositely rotate lever IT. The tension in rods 33 and 2| operate jointly through link I5 upon the pedal 9 at a point above its pivot, exerting a force tending to rock the pedal clockwise. This force is felt by the operators foot and gives a feel which is proportional to the force of brake application.

The normal application is not interfered with by the inertia device controlled by lever 59. However, should the brake application be unduly severe the inertia of weight 6| will cause it to rotate clockwise and by means of parts 63 and 65 to close openings 55, thus cutting off the ad-,

mission of air to the chamber 39 and resisting the movement of the piston by suction. Such action as this may occur on a slippery road which offers minimum traction for the wheels. Severe brake application under such circumstances easily stops the wheel rotation and causes the wheel to slide. This ineifective brake application is minimized by the present invention because the inertia of weight 5 I while the brake is applied, causes the closure of openings 55 and prevents further braking pressure. To control the extent of the influence of the weight the tension of spring I! against which the weight must act may be adjusted by the manipulation of knob 15.

In Figure 2 the inertia weight is used to similarly modify the action of a power cylinder, one side of the piston of which cylinder is constantly open to the atmosphere. In this figure IllI is the pedal held to brake-released position by spring I03. This spring may be anchored to any convenient part as to a frame member I55. The power cylinder I07 carriers a piston I09 to which is secured a rod I I I, the latter intended to be connected to any suitable brake rodding in such a way that the brake is applied by a move-.

. ing to the power cylinder at the left of the piston.

Suitable openings I21 keep the chamber of the cylinder at the right of the piston continuously open to the air. If the pedal is depressed passage I25 may be made to communicate with a passage I29, a cylinder I3I, and a conduit I33, the latter leading to the engine manifold. Within the cylinder I3I is a valve I35 connected to an arm of lever I31, the latter having a weight I39. The lever is shown pivoted to the bracket H3 at MI. The lever I31, when at rest and in engagement with its stop Bil, holds valve I35 in the position shown. Valve I35 will close the communication between the conduit I33 and the passage I29 when the lever swings clockwise. Such swinging is resisted by a spring I43 attached to the lever near the weight I39 and to a cable or rod I45 reciprocable through a cable housing I41.

This housing is anchored at one end to a bracket arm I59 and at its other end to the instrument board I. On the end of the operating cable is a knob I5 as before.

This second form of the invention operates in much the same way as the other except that the pedal in this form of the invention functions solely to control the fluid power actuator. When the pedal shifts the valve IE5 to render the suction. line operable through the passages I29 and I25, the unbalanced pressures in the cylinder I0! cause the piston to move to the left and apply the brake. In the event that the brake pressure is too great for the wheel traction, the weighted lever I31 swings clockwise so that the valve I35 closes the suction conduit. This action is re sisted by spring M3, and the tension of this spring is controlled by operating the flexible cable from the instrument board as before.

In the event that the Weighted lever should be too abrupt in its action, it is obviously possible to introduce any desired form of modifying means. To that end I have shown cylinder ISI somewhat elongated, and carried by the valve rod I31! within the cylinder is a second apertured piston member I32. The reciprocation of the piston I 32 provides a dashpot effect to prevent undesired movementsof the valve I35 under the influence of the pendulum member I3'l.

I claim:

Control mechanism forthe brakes of a vehicle having an operators compartment, a cylinder, a piston therein, said cylinder and piston constituting a fluid motor, connections from the piston for applying brakes, valve means to control the flow of gaseous medium to and from one side of said piston whereby the piston is caused to move under unbalanced pressure, manually operable means to control said valve, a pivoted weight and means actuated by said weight when the latter swings upon its pivot under the influence of inertia to modify the action of said fluid motor together with yielding means resisting the movement of said weight under the influence of inertia, and means connected to said yielding means and extending to the operators compartment whereby the tension of said yielding means may be adjusted.

JOHN H. HUNT. 

